BOSTON (Reuters) - Viewing the reflected image of an intact
limb in a mirror can fool the mind into thinking that a lost
leg or foot still exists, dramatically relieving phantom limb
pain, researchers reported on Wednesday.

At least 9 out of 10 amputees report feeling
sometimes-severe pain in the missing limb, often the result of
a sensation that the arm or leg is stuck in the wrong position.
The sensation can be excruciating and pain drugs often do
little to help.

But some studies have suggested that using a mirror to
trick the mind into thinking the lost limb is still there may
help. Doctors do not understand why it works, but it appears to
help a confused brain reconcile sensations coming from the
severed nerves.

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Dr. Jack Tsao, a Navy neurologist at the Walter Reed Army
Medical Center in Washington, asked 22 volunteers, most of whom
had lost part of a leg in Iraq, to try one of three therapies.

With the mirror technique, patients saw a reflected image
of their intact limb as they spent 15 minutes a day trying to
move legs and feet. The setup gave the illusion that the
missing limb was present and moving normally.

Another group looked at a mirror covered by an opaque sheet
as they tried to perform the same task. A third group was asked
to close their eyes and spend 15 minutes imagining their limb
moving normally.

During the first four weeks of treatment, pain intensity
dropped dramatically in the mirror group, going from an average
score of 30 to about 7 on scale up to 100. Every person in that
group reported less pain.

For those looking at the covered mirror, their average pain
score increased to about 60, in part because only one volunteer
said he felt less pain while three said their pain became
worse.

Among people who imagined their limb moving, the pain score
increased to about 60 after the first week, but then rapidly
diminished.

Then, during the next four weeks, all the patients were
switched to the mirror technique. Their pain scores diminished
significantly in eight out of nine cases.

"The majority of people got some relief. The range went
from some relief to completely gone," Tsao said in a telephone
interview. "We were surprised that the effect was so strongly
positive.""

The team is planning a similar test in people who have lost
arms.

The idea of mirror therapy has been around for at least a
decade, but it has not been widely adopted because "there's
never been a controlled study done before," Tsao said.

The technique may relieve pain by helping the brain
reconcile what the body is feeling with what the eyes are
seeing, Tsao said.

"Although the underlying mechanism accounting for the
success of this therapy remains to be elucidated, these results
suggest that mirror therapy may be helpful in alleviating
phantom pain in an amputated lower limb," his team wrote in a
letter to the New England Journal of Medicine.